Many conventional oil wells have been abandoned even though large quantities of extractable oil remain, as a result of the relatively high cost of known enhanced oil recovery techniques. In addition, there exist, throughout the world, large deposits of heavy and bituminous oils from which recovery is difficult and expensive.
Proposals have been made to recover bitumen from oil sand deposits and heavy oil deposits occurring in the Athabasca region of Alberta, Canada by the utilization of steam to render the bitumen flowable and the removal of the bitumen from the deposit in suspension in hot water under the influence of steam pressure. After separation of the bitumen from the aqueous phase, there remains an aqueous medium which is contaminated with residual hydrocarbons and minerals.
The contaminants inhibit the reutilization of this water for steam production, since the minerals scale reboiler tubes and the hydrocarbons cause fouling of boiler parts. Substantial volumes of water are required for the steam extraction procedure and the inability to utilize the aqueous medium imposes a considerable strain on the limited water resources of the region and also poses a considerable disposal problem.